Thursday, October 29, 2015

Lone Survivors

A million years ago, our Homo
erectus ancestors consisted of maybe 20,000 breeding individuals, according
to wizards who speculate on the hidden secrets of DNA.This is similar to the current population of
chimpanzees or gorillas.The ancestors
lived in scattered pockets of Africa, at a time when Earth was a paradise of
abundant life.From these ancient roots,
a number of hominid species evolved, but only Homo sapiens still survives, at seven-point-something
billion and growing.The chimps and
gorillas continue to live in a manner similar to their ancestors of a million
years ago.What happened to us?

Chris Stringer is one of the venerable grandfathers in the
study of human evolution.He’s read the
papers, attended the conferences, examined the skulls, and had a ringside seat
at the noisy catfights.This field of
knowledge is far from finished.New specimens
continue to be found, and new technology provides deeper insights.Stringer’s book, Lone Survivors, discusses some primary
issues, and the scholarly disputes surrounding them, as they stood in 2012.He does a pretty good job of providing an
overview to a huge and complex subject, but readers with little background are
advised to wear life preservers.

I learned a lot about Neanderthals.They survived 400,000 years on a climate
change roller coaster.They hung out
with hippos in warm forests near Rome, and they chased wooly mammoths on frigid
treeless tundras.They had short, stocky
bodies that were good for preserving heat, but which required more calories.Males and females were about the same size,
suggesting little division of labor, everyone joined in the hunt.

The Neanderthal diet majored in the flesh of large game.Readers who have hunted hippos with wooden thrusting
spears know that his is very dangerous.One site in Croatia contained the remains of 75 Neanderthals, and none
were older than 35.In their clans, there
were probably many orphans and few grandparents.The scarcity of elders, and the small size of
their groups, sharply restricted the flow of cultural information from one
generation to the next, and from clan to clan.

Some say that Neanderthals lacked shoes and close-fitting
clothing.When Darwin visited chilly
Tierra del Fuego, at the bottom of South America, he was shocked to see natives
wearing little or no clothing and sleeping naked in the open.Stringer noted that modern Europeans seem to
be poorly adapted to the cold, physiologically.

Cro-Magnons were the Homo
sapiens that moved into Europe maybe 45,000 years ago.European Neanderthals disappeared around
30,000 years ago.Neanderthals went
extinct in the Middle East, Siberia, Gibraltar, and Britain at different times,
probably for different reasons.This was
an era of frequent climate zigzags.When
temperatures plummeted, habitable territories shrank, and fewer folks could be
fed.

Cro-Magnons apparently had footwear and warm, fitted
clothing.They had better tools for
hunting, so their diet was more diverse and dependable.They were able to extract more nutrients from
an ecosystem, so they could survive in places where Neanderthals could
not.They lived in larger groups, and
more of them survived to middle age or old age, so more cultural information
could be passed to the young.

Large populations are better at preserving cultural
knowledge, acquiring new information from outsiders, and generating
innovations.More busy minds interact,
exchange ideas, compete, and imagine cool ways for living even farther out of
balance.Witness the city of Los
Angeles, where 14 million animals with hunter-gatherer DNA are temporarily able
to survive because of a highly complex system of innovative technology.Note that this innovation has no relationship
to foresight or wisdom.Time is running
out on Los Angeles.

On the other hand, less innovation occurs in smaller simpler
groups, and that’s often a blessing.Innovators can be dangerous loose cannons, introducing risky new ideas
that result in horrid unintended consequences — like cell phones, automobiles,
or agriculture.Nothing is more precious
than a stable, sustainable, time-proven way of living, where the secret to
success is simply imitating your ancestors, conforming to the norm, and
enjoying life, like the chimps and gorillas do.

When the planet heated up 14,000 years ago, rising sea levels
submerged the land link between Australia and Tasmania, terminating the exchange
of people, ideas, and gadgets.Tasmania’s
traditional way of life was also squeezed as the warmer climate spurred the
expansion of heavy forest.The natives
experienced a cultural meltdown.“Tasmanians
appear to have led an increasingly simplified life, forgoing apparently
valuable skills and technologies, such as bone and hafted tools, nets and
spears used to catch fish and small game, spear throwers and boomerangs, and
anything but the simplest of skin clothing.”

Will climate change have a similar effect on industrial
civilization in the coming decades?Will
it slash food production, sharply reduce population, eliminate travel between
regions, pull the plug on modern technology, and erase lots of obsolete and
unsustainable cultural information?Could collapse have a silver lining?

Climate change can derail any culture, and drive species to
extinction.It can also produce
beneficial conditions, like the unusually favorable climate of the last 10,000
years.Natural selection rewards species
that can adapt to change, and it deletes those that fail.There is another important variable that is
often overlooked — genetic drift — mutations that happen all the time when
slight boo-boos occur during cell division.These tiny defects can provide a barrel of surprises.

We are repeatedly taught that humans are nature’s flawless masterpiece,
the glorious conclusion of three billion years of evolution.But, if Big Mama Nature had experienced slightly
different moods over the eons, we might be Neanderthals or Denisovans today (or
maybe slime mold).Climate change and genetic
drift are purely random. The fact that Homo sapiens is the
lone survivor among the hominid species is not absolute proof of superiority,
but it does indicate a temporary streak of good luck.

Homo
heidelbergensis was an ancestor that lived 500,000 years ago.They had brains ranging in size from 1100 to 1400
cc (modern brains average 1350 cc).The
average Neanderthal brain was 1600 cc — much bigger than ours.Stringer noted that our brains today are ten
percent smaller than our Homo
sapiens ancestors of 20,000 years ago. Is there a message here?

Without words, chimps and gorillas can express contentment,
affection, irritation, excitement.But without
complex language, they are more trapped within themselves.Language took us “into new and shared worlds
that were unknown to our ancestors.” We
can talk about the here and now, the past, the future, abstract concepts, feelings,
imaginary worlds, and so on.

Later, innovative geniuses invented the use of symbols.Now we can convert words into patterns of
squiggly lines, for example: “computer.”Writing enables us to communicate with folks in faraway places.I can read words written by Julius Caesar, and
so might the generations yet-to-be-born, in theory.Industrial civilization cannot exist without
symbols — numbers, graphs, pictures, status symbols.Progress abounds with powerful and dangerous
juju.

Stringer is a mild mannered humanist.And so, he portrays the human journey as one
of admirable advancement (the chimps fall down laughing).On the last page, he confesses a profound
doubt.“Sometimes the difference between
failure and success in evolution is a narrow one, and we are certainly on a
knife edge now as we confront an overpopulated planet and the prospect of
global climate change on a scale that humans have never faced before. Let’s hope our species is up to the
challenge.”

Stringer, Chris, Lone
Survivors: How We Came to Be the Only Humans on Earth, Times Books,
New York, 2012.

2 comments:

Not only have our much-vaunted brains become smaller (and size does matter in terms of the number of neural connections), but our health has diminished greatly.

Today, we learn that processed red meat is bad for us, but that ignores the sickly nature of both our bodies and our meat-producing industry, and the unnaturally-prolonged lives that invite systemic diseases.

We continue to think of the Neolithic "revolution" - the shift from "barbarism" to a settled agricultural and eventually "civilized" life, as a profoundly positive development.

Yet Paleo-archeology has demonstrated that, everywhere in the world, the transition from hunting and gathering to a grain-based diet resulted in stunted growth, more bone lesions indicating infections, considerably more dental carries (cavities), and shorter lifespans.

Many see the Neolithic Revolution (or Agricultural Revolution) as the turning point in the human journey, when we got booted out of Eden and became farm animals. The good old days were over. Without a doubt, in the long run, the costs have far exceeded the benefits.

Stringer mentions an earlier revolution, which he calls the Human Revolution — the glorious arrival of human modernity — complex language, cave painting, expanded social networks, amazing technology, and so on. Some imagine that there was a brain mutation that turbocharged our thinkers, and it happened about 50,000 years ago. Diamond, Ehrlich, and Flannery call it the Great Leap Forward.

Stringer thinks it happened in Africa, maybe 100,000 years ago, as growing population density enabled a surge of innovation.